Choosing the Right Core Count and Shield Type for Your Job
Quick Answer
Use 4 core for basic door and window contacts. Use 6 core for keypads, sirens, and powered sensors. Use 8 core where a single run needs to carry a combined circuit, such as a reader with tamper or LED feedback. Stay unshielded unless the run sits near power or serves an access control reader, where shielded is worth the extra cost.
Security and alarm cable looks simple from the outside, a jacket with a handful of coloured conductors inside, but getting the core count and shield type wrong is a common cause of comeback jobs. Running 4 core where the job needed 6, or unshielded where the run sits next to a power cable, means pulling new cable through a wall that is already closed up. Getting it right the first time comes down to two questions, how many conductors does the job actually need, and does the run need shielding against interference.
4 Core, 6 Core or 8 Core
Core count is driven by what is on the other end of the cable, not by habit or whatever is already on the reel.
4 core covers most non-powered devices, door and window contacts, reed switches, and basic zone wiring where the device only needs a simple open or closed circuit reporting back to the panel. Two cores carry the signal, the other two are commonly used as a spare pair or for a second zone on the same run.
6 core is the standard choice once a device needs power as well as signal, most keypads, powered motion detectors, and sirens fall into this category. Two cores carry power, two carry signal, and the remaining two act as spares, which matters in practice because pulling a new cable after the walls are closed is far more expensive than running one extra pair on day one.
8 core is worth specifying where a single run needs to serve multiple devices or functions at once, for example a keypad with a built in reader, or a zone that combines a powered sensor with a tamper circuit. It costs more per metre than 6 core, so it is worth reserving for jobs that genuinely need the extra conductors rather than defaulting to it everywhere.
Shielded or Unshielded
Most alarm and security cable runs are unshielded, and for the majority of standard installs that is the correct choice, shielding adds cost and stiffness without adding benefit if there is no interference source nearby.
Shielded cable earns its place in a few specific situations. Runs that travel alongside mains power cabling, through switchboards, near fluorescent or LED drivers, or near other sources of electrical noise benefit from a shield, since it drains interference away from the signal conductors before it can cause false triggers or communication errors. Access control readers and longer runs to powered devices are also commonly specified shielded, since these circuits are more sensitive to induced noise than a simple door contact.
As a working rule, if the cable run stays clear of power infrastructure and serves basic contacts or sensors, unshielded is fine. If it runs near power, serves a reader, or the job is one where a false trigger from interference would be a genuine problem, shielded is worth the extra cost.
Access Control Wiring
Access control jobs use the same core count logic as the rest of a security install, readers and strikes typically run on 6 core or 8 core depending on whether the reader also needs a tamper or LED feedback circuit, and shielded cable is the more common choice given how close these runs often sit to door hardware and power. If you are colour coding a run yourself, our internal cable colour code and external cable colour code references cover the standard conductor colours used across security and data cabling.
Stranded vs Solid
Security cable is available in both stranded and solid conductor versions. Stranded is easier to work with in tight terminations and holds up better where the cable will flex or be handled repeatedly, such as at a keypad or reader. Solid conductor is more common on long fixed runs where the cable is terminated once and left undisturbed.
Quick Reference
| Application | Typical Core Count | Shielding |
|---|---|---|
| Door and window contacts | 4 core | Unshielded |
| Keypads, sirens, powered motion detectors | 6 core | Unshielded, unless run near power |
| Access control readers and strikes | 6 core or 8 core | Shielded |
| Combined zone and tamper circuits | 8 core | Shielded |
For camera specific cabling, including analogue versus IP camera cable types and outdoor installation practices, see our Security Camera Cabling Guide. If the job includes analogue or HD-over-coax cameras, our BNC Connector Types Explained page covers choosing the right connector for the coax run.
Frequently Asked Questions
Can I use 4 core cable for a powered device?
Not reliably. 4 core is designed for simple contact devices that only need a signal circuit. Powered devices such as keypads and sirens need two dedicated cores for power on top of the signal circuit, which is why 6 core is the standard choice for anything powered.
Do I need shielded cable for a standard door alarm?
No. A standard door or window contact run that stays clear of power cabling is fine on unshielded cable. Shielding is worth specifying when the run travels near mains power, switchboards, or lighting drivers, or when it serves an access control reader.
What is the spare pair in 6 core cable used for?
The spare pair covers future changes without pulling new cable, adding a second zone, upgrading a device, or wiring a feature that was not part of the original job. It costs very little extra at install time compared to opening a wall again later.
Should access control cable always be shielded?
It is the more common and generally safer choice, since readers and strike wiring often run close to door hardware and power infrastructure that can introduce interference. It is not an absolute rule, but it is worth defaulting to shielded unless you have a specific reason not to.
Is stranded or solid conductor cable better for security cable?
Stranded is easier to terminate and holds up better with repeated handling, which suits keypads and readers. Solid conductor suits long fixed runs that are terminated once and left undisturbed.
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